Exactly, I was only 1500 when I went random civs and then I start to pick Mayans if they pick and I became a mayans one trick (trust me noone had that random option on) and I started to beat 1700s just with drush fc. Some strategies are broken with certain civs. I don't want to call them "cancer" but they are certainly unfair.That you are not 1700, and I'll wager your real rate ("with any civ") is around 1600, perhaps a bit less, depending on when you started doing only inca vil rush - as you can imagine, by using only the same strat every game you also degenerate as a player; maybe your rating went above 1600 with inca vil rush, but this does not always mean you actually improved.
Based on your player statistics, you would be delusional to think that you can play at 1600 level with more than 3 or 4 civs.